With the development of the mobile network service and automation control technology, a machine type communication mode also called a Machine To Machine (M2M) communication mode appears, and in the communication mode, at least one party participating in the communications is a machine device.
In a narrow sense, a definition of M2M is the communications from machine to machine, but in a broad sense, the M2M includes networking applications and services which are centered on machine terminal intelligent interaction. The M2M can provide informationized solutions for clients based on intelligent machine terminals and using various communication modes as access methods, which are used for satisfying informatization demands of users on monitoring, command scheduling, data acquisition and measurements and so on. The M2M can be applied to industry applications (such as traffic monitoring, alarm system, maritime rescue, vending machine and pay-for-drive and so on), family applications (such as automatic meter reading and temperature control and so on) and personal applications (such as life detection and remote diagnosis and so on), etc.
A communication object of the M2M is a machine, and a communication behavior is in automation control, that is, initiation and termination of the communication and the control on certain admissions and restrictions in the communication process are all automatic behaviors. This kind of behavior relies on the restriction and control on the machine (i.e. a terminal in M2M communication) behaviors in the M2M communication, and the behaviors of the terminal in M2M communication are restricted by service subscription data, and a network manages the terminal in M2M communication according to the service subscription data.
The most typical communication mode in machine type communication is communication between a terminal and an application server, and the terminal is called as a Machine Type Communications device (called as an MTC device for short) or an MTC UE, and the application server is called as an MTC Server.
In the 2G/3G/LTE access, a Packet Service (PS) network is mainly used as a bottom layer bearer network in the M2M communication, which implements service layer communications between the MTC device and MTC server. FIG. 1 is a schematic diagram of architecture of an M2M communication entity accessing an Evolved Packet System (EPS) according to the related art. As shown in FIG. 1, the bottom layer bearer network includes: an Evolved Universal Terrestrial Radio Access Network (E-UTRAN), a Mobility Management Entity (MME), a Serving Gateway (S-GW or SGW), a Packet Data Network Gateway (PDN GW, P-GW, or PGW), a Home Subscriber Server (HSS) and a Policy and Charging Rules Function (PCRF). Wherein, a major network element of the E-UTRAN is an Evolved NodeB (eNodeB).
In FIG. 1, the MME takes charge of works such as mobility management, non-access layer signaling processing and context management in user mobility management and so on related to a control plane; the S-GW is an access gateway device connected with the E-UTRAN, which takes charge of forwarding data between the E-UTRAN and P-GW and caching the paging waiting data; the P-GW is a border gateway of the EPS and a Packet Data Network (PDN), which takes charge of functions such as access of the PDN and data forwarding between the EPS and PDN and so on; and the PCRF is a policy and charging rules function entity, which is connected with an Internet Protocol (IP) service network of operators through a receiving interface Rx to acquire service information. Moreover, the PCRF also can be connected with a gateway device in the network through a Gx interface, which takes charge of initiating IP bearer establishment and guarantees the Quality of Service (QoS) of service data, and performs charging control. The HSS is used to provide the managements of subscription data of the users and the management of important context information accessed by the users to the network.
In addition, the MTC Server can play the role of an Application Function (AF), which is connected with the PCRF through the Rx interface so as to implement control on the bearer. Moreover, the MTC Server can play the role of a Session Initiation Protocol Application Server (SIP AS), which is connected with the HSS through a Sh interface so as to access application service data.
In FIG. 1, the MTC UE accesses an EPS network through the E-UTRAN (eNodeB), after an IP address is allocated to the MTC UE, an IP tunnel can be established between the MTC UE and MTC Server, thereby implementing upper layer service communications between the MTC UE and MTC Server. The IP tunnel established between the MTC UE and MTC Server is a logical IP tunnel of which a physical path goes through: eNodeB, S-GW, P-GW.
Currently, one way to implement the M2M communication is to establish one service layer interface protocol on the IP tunnel between the MTC UE and MTC Server, and the service data interaction is performed between the MTC UE and MTC Server through the service layer interface protocol. Meanwhile, the MTC Server also implements control on the MTC UE through the service layer interface protocol.
Through an IP connection between the MTC UE and MTC Server, data communication between the MTC UE and MTC Server can be implemented, but MTC monitoring demands that, the MTC Server needs to monitor a running state of the MTC UE and acquire the current state of the MTC UE timely and dynamically, and when the current state of the MTC UE is changed, MTC Server needs to obtain a timely notification, are extremely difficult to be implemented on the IP connection. These state changes of the MTC UE may include: the MTC UE detaching from the network, the MTC UE entering into a disconnected state, the MTC UE releasing a wireless connection and the current position of the MTC UE being changed and so on. These state changes of the MTC UE can be called as one MTC event. Generally, which MTC events are required to be monitored can be defined in MTC subscription data of Home Location Register/Home Subscriber Server (HLR/HSS) and sent by the HLR/HSS to Serving GPRS Support Node (SGSN)/MME through the procedure of the MTC UE attaching to the network. However, with regard to the detection of the MTC events, network entities of a core network is generally required to perform the detection, e.g. in the EPS network, network elements which are responsible for detecting the MTC events can be MME/SGW/PGW and so on, and in a General Packet Radio Service (GPRS) network, network elements which are responsible for detecting the MTC events can be SGSN/Gateway GPRS Support Node (GGSN) and so on. After the MTC events are detected, it is generally required to make a report to the MTC Server so that the MTC Server can acquire the running condition of the MTC UE in time.
After network congestion occurs, the MME can refuse an access request to a certain MTC device group or a certain Access Point Name (APN).
In a network attachment process, the MME obtains a group identifier to which the MTC device belongs through the HSS. When receiving access requests of the MTC device, the MME can refuse those access requests of the MTC device which belongs to a group causing the congestion according to the current congestion condition and the group identifier to which the MTC device belongs. In addition, the MTC device also can include the group identifier in an access request message so that the MME can make a fast judgment on the access requests.
The MME provide back off time in a rejection message, and the MTC device which is refused to access needs to wait for a period of time (a duration indicated by the back off time) and then initiate the access requests again. The specific flow is as shown in FIG. 2, and the following steps are included.
In step 201, an MTC device sends an access request message to an MME, and the access request message can include a group identifier to which the MTC device belongs.
In step 202, the MME decides whether to permit the access of the MTC device according to the current network load condition and the group identifier to which the MTC device belongs.
In step 203, the MME sends an access request acceptance message or an access request rejection message to the MTC device. A back off time parameter is included in the access request rejection message to indicate a waiting duration.
With the above method, not only a large quantity of network signaling resources are occupied, but also user experience is reduced when using the services.